Will Carington, works for Noodle
According to the US Department of Homeland Security's website, the Form I-20, or "Certificate of Eligibility for Nonimmigrant Student Status," will be given to you by a designated school official once you are accepted to a Student and Exchange Visitor Program (SEVP)-certified school. If you are planning to study at Edison High School but have not yet received this form, my advice would be to contact the school directly at 714-962-1356. Another option is to email the guidance office.
For more on this topic, make sure to check out Noodle's resources for studying in the U.S. for international students. Hope this helps, and best of luck!